Fire check Flush doors

Building regulation require certain doors to be able to resist the spread of fire for periods of half or one hour depending upon the sice and type of building.

Half-hour fire door (FD 30 )
A standard half hour fire door is constructed with a skeleton core to which 9.5mm thick plasterboards are fixed in rebates ins tiles and rails and over which the 3mm plywood facings are glued.

One hour fire door (FD 60 )
Flush door which are constructed to give one hour's protection have a skeleton core and 9.5mm , plasterboard infilling , with 6mm cement particle board , below the plywood facings.

Fire foor frames
These doors are hung in frames with specially deep rebates , so that fire will not easily spread around the edges of these doors.

To achieve this , they must be used in conjunction with the correct frame:

• FD 30 required a two-piece frame with a planted (nailed ) stop to form a deep rebate.
• FD 60 required a solid frame with a recess cut in the door frame to form a deep rebate.

Smoke resistance

• An effective barrier to smoke and flame is an intumescent strip fitted to the door edge or integral with the frame
• Use of intumescent strip is usually the most practical , being secured in a frame recess with a rubber-based or PVA adhesive.
• At temperature of about 150 Celcius , the seal expands to prevent passage of fire and smoke for the designated period.
• The seal will not prevent door movement for accesss and escape of personnel.
• FD 30 with two-piece frame olny required single intumescent strip
• FD 60 with solid frame required dual intumescenet strip

Fire door fittings

1. Half-hour fire doors are hung using one pair of hinges , whereas one-hour doors require one-and-a-half pairs of hinges
2. All the fire doors should have an automatic self-closing device . The door closers that are used are overhead door closers.
3. The oeverhead door closers consist of a hydraulically operated cylinder in a metal casing that is either screwed to the door face or set in a housing in the top of the door leaf for appearance sake.
4. Pivoted arms , one to the housing and one attached to the door frame , act to automatically close the door to the frame , after the door has been opened.